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Old 07-30-10, 02:54 PM   #1
medusa
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threaded to threadless?

In my attempt to find a rigid steel fork.. I see a predominant number of them are threadless.
My glove has a threaded fork. If I can if I buy a threadless fork can I switch it out and what more if anything else would I need to change?
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Old 07-30-10, 03:09 PM   #2
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Headset, stem and some new bar tape. you will probably need some spacers.
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Old 07-30-10, 06:04 PM   #3
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Headset, stem and some new bar tape. you will probably need some spacers.
ok....uugh...thank you for the info .
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Old 07-30-10, 06:47 PM   #4
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You need to make sure that your new threadless fork has the same steer tube diameter. They come in 1" and 1 1/8. The problem in making the transition is that 1 1/8 threaded forks are rare and 1" threadless forks are difficult to find.

Also, you mention that you are looking for a "rigid" fork. Am I to presume your bike currently has front suspension? If so, then you need one that is suspension corrected.
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Old 07-31-10, 02:48 AM   #5
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When MrCjolsen says "suspension corrected" he is referring to the fact that suspension forks are typically taller, axle to crown, than non-suspension forks. They may also have less rake.

Bike frames are designed for a specific fork height and rake. If the new fork is shorter you end up with steeper headtube and seattube angle and a lower bottom bracket. This can be good or bad, but if you want similar handling with the new fork you need to measure the current forks axle to crown height minus sag.

To measure sag I've generally heard you should place a zip tie, snug enough that it will stay in place, at the bottom of one stanchion, ride the bike a short distance on a flat surface, get off, and measure how high the tie is.
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Old 07-31-10, 07:17 AM   #6
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Headset, stem and some new bar tape. you will probably need some spacers.

I think one could argue about the need for a new headset:
You can use a good fitting spacer or also just file off the inner threads of the locknut a little bit until it can be slided over the new unthreaded steerer tube. Then for sure additional spacers might be needed above, also a star nut (but the replacement unthreated fork might have that) and a cap. All has to have he same diameter. Also the issue of a possible exchange of crown race needs to be thought through.
See it positively, if you - with some persistence - for sure will succeed, you have advanced honors!
On ebay you can find cheaply all kind of used forks (rigid and suspension) with all steerer tube diameters, both threaded and unthreated.
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Old 07-31-10, 07:39 AM   #7
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I think one could argue about the need for a new headset:
You can use a good fitting spacer or also just file off the inner threads of the locknut a little bit until it can be slided over the new unthreaded steerer tube.
Done right, this is a job for a machine shop, not someone with a file. Yes it can be done and was done years ago by Pro team mechanics to allow Shimano threaded headsets to be used on threadless steerers but they had access to the proper equipment.

New threadless headsets aren't that expensive. Get the right one.
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Old 07-31-10, 07:56 AM   #8
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threaded to threadless

Thank for the tip on the zip tie trick....neat . I do know I have a 1 1/8 threaded fork now with a 65MM rake ( whatever that is)... I've read where I can have about a 10-15MM variance on my new fork but there was no mention of only buying one that said suspension corrected ( again --whatever that is) . Am I to assume that is one does not say suspension corrected I cannot consider it as a viable replacement. So far any of those that have mentioned rake ( and many of them don't) I haven't seen any that mentions a 65mm rake. I'm sure I could get my threadless threaded....I don't mind getting a new headset but having to replace the stem as well......jeesh it seems like a domino effect with a bike.....replace one part..replace beacoup others.
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Old 07-31-10, 09:56 AM   #9
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This isn't as hard as they make it sound. A cheap headset can be had on eBay for 20 bucks, a stem can also be had for 15 bucks. A fork doesn't go straight down to the axle, there is always either a gentle curve or an angle forward, that angle forward is the rake. More rake and it stretches out the geometry, less does the opposite.
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Old 07-31-10, 10:02 AM   #10
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One place to find suitable forks is an older bike shop. Many rigid MTBs were upgraded to suspension forks and the old rigid forks can be had for a song. My LBS must have 50 take-off forks in his back room and you can probably find something similar. As noted, a decent threadless headset isn't that expensive and neither is a suitable stem.

Threading a threadless steerer is difficult and most bike shops won't do it.
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Old 08-02-10, 06:10 AM   #11
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A non suspension fork can be, and typically is, shorter than a suspension fork. If a suspension fork has 100mm of travel, it can compress to be 100mm shorter than it is when not under load. That means it starts out 100mm taller to offer the same clearance for the wheel then a rigid fork would need to.

If you have a suspension fork with 60mm of travel, and the sag (compression from just your weight) is 10mm to 15mm, you can probably get a used rigid fork that was not meant to replace a suspension fork (I.e. not "suspension corrected") and it will be close enough. Many rigid forks (in my experience) have slightly more wheel clearance than most suspension forks. The head tube would be 1/2" to 1" lower, and you probably wouldn't notice a serious change in steering.

If you have 80mm of travel you should probably get a "suspension corrected" fork. It doesn't have to say suspension corrected; it just needs to be taller (axle to crown) than a typical rigid fork so the head tube doesn't end up several inches lower.

If you have 100mm of travel you may want to consider making it a 96'er, but that would mean even more parts to buy.
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